Apparatus with vertical and lateral movable means for handling groups of radioactivesamples



June 21, 1966 E. FRANK ETAL 3,257,009

APPARATUS WITH VERTICAL AND LATERAL MOVABLE MEANS FOR HANDLING GROUPS OF RADIOACTIVE SAMPLES Filed April 15, 1963 17 Sheets-Sheet 1 TRAY SELECTOR I cYcLEs 9 PER TRAY] SAMPLE CHANGER If) 3 8 47 l STOP /0PE RATE Z /l r INVENTORS EDWARD F; POLIC EDMUND FRANK BY n y, W Ka /0M ATTORNEYS June 21, 1966 E. FRANK ETAL APPARATUS WITH VERTICAL AND LATERAL MOVABLE MEANS FOR HANDLING GROUPS OF RADIOACTIVE SAMPLES Filed April 15, 1963 1'7 Sheets-Sheet 2 ATTORNEYS June 21, 1966 E. FRANK ETAL 3,257,009

APPARATUS WITH VERTICAL AND LATERAL MOVABLE MEANS FOR HANDLING GROUPS OF RADIOACTIVE SAMPLES Filed April 15, 1963 17 Sheets-Sheet 5 INVENTORS EDWARD F. Pou

' 37 BY EDMUND FRANK ATTORNEYS June 21, 1966 E. FRANK ETAL 3,257,009

APPARATUS WITH VERTICAL AND LATERAL MOVABLE MEANS FOR HANDLING GROUPS OF RADIOACTIVE SAMPLES Filed April 15. 1963 1'? Sheets-Sheet 4 M9, #1, g/z 11/ ATTORNEYS June 21, 1966 E. FRANK ETAL 3,257,009

APPARATUS WITH VERTICAL AND LATERAL MOVABLE MEANS FOR HANDLING GROUPS OF RADIOACTIVE SAMPLES Filed April 15, 1963 17 Sheets-Sheet 5 INVENTORS EDWARD F. POLIC EDMUND FRANK BY My, 40kg Kv QM ATTORNEYS June 21, 1966 E. FRANK ETAL 3,257,009

APPARATUS WITH VERTICAL AND LATERAL MOVABLE MEANS FOR HANDLING GROUPS OF RADIOACTIVE SAMPLES Filed April 15, 1963 17 Sheets-Sheet 6 INVENTORS EDWARD F. POLIC EDMUND FRANK BY ATTORNEYS E. FRANK ETAL June 21, 1966 APPARATUS WITH VERTICAL AND LATERAL MOVABLE MEANS FOR HANDLING GROUPS OF RADIOACTIVE SAMPLES Filed April 15, 1963 1'7 Sheets-Sheet '7 SC S U a WOMd b O v T F MT mDW/A RM D HE D E BY My,

June 21, 1966 E. FRANK ETAL APPARATUS WITH VERTICAL AND LATERAL MOVABLE MEANS FOR HANDLING GROUPS OF RADIOACTIVE SAMPLES Filed April 15, 1963 l? Sheets-Sheet 8 INVENTORS EDWARD F. POLIC BY EDMUND FRANK Nfi W wifdM ATTORNEYS June 21, 1966 E. FRANK ETAL 3,257,009

APPARATUS WITH VERTICAL AND LATERAL MOVABLE MEANS FOR HANDLING GROUPS OF RADIOACTIVE SAMPLES l7 Sheets-Sheet 9 Filed April 15, 1963 INVENTORS EDWARD F. POLIC EDMUND FRANK ATTORNEYS June 21, 1966 E. FRANK ETAL 3,257,009

APPARATUS WITH VERTICAL AND LATERAL MOVABLE MEANS FOR HANDLING GROUPS OF RADIOACTIVE SAMPLES Filed April 15, 1963 17 Sheets-Sheet 10 1/1 1 1;; J2 f ZZZ i 1/4 122 z; 1 111 12/ AIIH I llllllllllI]llllllll(lllIlll(V/Y W K /1z g l I 7 .1%. Q

INVENTORS EDWARD F. POLIC DM F B E UND RANK ATTORNEYS J1me 1966 E. FRANK ETAL 3,257,009

APPARATUS WITH VERTICAL AND LATERAL MOVABLE MEANS FOR HANDLING GROUPS OF RADIOACTIVE SAMPLES Filed April 15, 1965 17 Sheets-Sheet 11 r YIIIIIIIIA IIIIIIIIIII INVENTORS k up-n-n-n-g...

EDWARD F. POLIC EDMUND FRANK ATTORNEYS INVENTORS POLIC EDMUND FRANK EDWARD F.

BY W/QMM 1'7 Sheets-Sheet 12 E. FRANK ETAL APPARATUS WITH VERTICAL AND LATERAL MOVABLE MEANS FOR HANDLING GROUPS OF RADIOACTIVE SAMPLES June 21, 1966 Filed April 15, 1963 ATTORNEYS June 21, 1966 E. FRANK ETAL 3,257,009

APPARATUS WITH VERTICAL AND LATERAL MOVABLE MEANS FOR HANDLING GROUPS OF RADIOACTIVE SAMPLES Filed April 15, 1963 1'? Sheets$heet 1s INVENTORS EDWARD F. POLIC r lI-lI-L' I u I I I I l l III\ B EDMUND FRANK @84 W w ry/MK ATTORNEYS June 21, 1966 E. FIQANK ETAL APPARATUS WITH VERTICAL AND LATERAL MOVABLE MEANS FOR HANDLING GROUPS OF RADIOACTIVE SAMPLES l7 Sheets-Sheet 14 Filed April 15, 1963 Mfg [41 g /M ATTORNEYS June 21, 1966 FRANK ETAL 3,257,009

APPARATUS WITH VERTICAL AND LATERAL MOVABLE MEANS FOR HANDLING GROUPS OF RADIOACTIVE SAMPLES Filed April 15, 1963 1'? Sheets-Sheet l5 INVENTORS EDWARD F. POLIC EDMUND FRANK BY #84, W, V; a.

ATTORNEYS J1me 1966* E. FRANK ETAL 3,257,009

APPARATUS WITH VERTICAL AND LATERAL MOVABLE MEANS FOR HANDLING GROUPS OF RADIOACTIVE SAMPLES 1'7 Sheets-Sheet 16 Filed April 15, 1963 INVENTORS POLIC Y EDMUND FRANK 7/2 g/ ffl ATTORNEYS EDNARD F OOOOOOOOO OO OOOOOOO June 21, 1966 E. FRANK ETAL 3,257,009

APPARATUS WITH VERTICAL AND LATERAL MOVABLE MEANS FOR HANDLING GROUPS OF RADIOACTIVE SAMPLES Filed April 15, 1963 1'? Sheets-Sheet 17 1 4f 41 /7X "d 7 //34 Ja /7114 74 002W Ill/[#712 634/. Jaw/m II/A/ZZ? 410:! 1 4/267! iii! i flP/A/ 1/ \J/ 74" -7 [Z f/XII \ff fins/4M mmvz Z @3 I INVENTORS EDWARD F. POLIC BY EDMUND FRANK ATTORNEYS United States Patent Oflice 3,257,009 Patented June 21, 1966 APPARATUS WITH VEliTICAL AND LATERAL MOVABLE MEANS FOR HANDLING GROUPS OF RADIOACTIVE SAMPLES Edmund Frank, Chicago, and Edward F. Poiic, Lisle, Ill., assignors to Packard Instrument Company, Inc., Brookfield, 111., a corporation of Illinois Filed Apr. 15, 1963, Ser. No. 273,120

13 Claims. (Cl. 21416.4)

The present invention relates in general to radioactivity measuring apparatus and, more particularly, to a transfer system suitable for use with such measuring apparatus for delivering and removing discrete groups, each containing a plurality of samples, to and from a sample indexing mechanism which permits of seriatim transfer of the individual samples to a radiation detection chamber. In its principal aspect, the invention is concerned with a transfer system for use in automatically transferring, upon demand, a given one of .a plurality of completely independent discrete groups of samples containing one or more radioactive isotopes and with each group stored at a different point, to a single station wherein the group may be indexed to sequentially align all of the samples with a detection apparatus for measuring the activity levels thereof. I

It is a general aim of the present invention to provide an improved and reliable transfer system characterized by its ability to shift, either sequentially or upon demand, given ones of a plurality of groups of such samples wherein the groups are completely separate and independent and stored at spaced points, yet wherein each group is rapidly and automatically shifted, one at a time, to and from a group indexing station. While not so limited in its application, the invention will find particularly advantageous use in research laboratories or similar environments wherein a number of technicians or individuals are engaged in separate experiments, thus making it desirable and oft-times requiring that the samples for each individual be segregated from the samples belonging to other individuals.

Another object of the invention is to provide a novel transfer system which facilitates the handling and processing of relatively large numbers of samples originating from different sources, and which permits such samples to be lowered to equilibrium temperature during such periods as previous samples are being indexed through counting cycles.

In another of its important aspects, it is an object of the present invention to provide a novel storage and transfer system for handling relatively large numbers of radioactive samples which are segregated into completely separate and independent groups originating from one or more sources, thus permitting technicians to remove one or more sample groups from storage or to insert one or more sample groups into storage, yet wherein such transposition of groups can be readily and simply effected without interrupting the indexing cycle of the group currently being processed in the detection apparatus. As a consequence of attaining this objective, large numbers of samples emanating from multiple points of origin can be continuously processed with both rapidity and reliability, and wherein the removal or insertion of other samples by ditferent technicians will not result in off-time for the apparatus.

Yet another object of the invention is to provide an improved multiple sample transfer system which permits groups of samples to be loaded into a sample tray at the point of origin of the samples, which point is located remotely from the detection apparatus, and wherein all of the samples in each tray will be automatically indexed through counting cycles without requiring the technician to load the samples individually into a sample changer,

time and the useful operating time of the detection apparatus.

In another of its important aspects, it is an object of the invention to provide a transfer system characterized by its ability to handle a plurality of groups of radioactive samples wherein the groups are sequentially transferred to and from an indexing station associated with a detection apparatus, yet wherein groups of samples containing one or more priority items can be handled out of turn and upon completion of such specialized treatment, the apparatus again resumes its sequential cycling.

Yet another object of the invention is to provide a compact sample changing apparatus whichpermits storage of a plurality of groups of samples in spaced stacked relationship and wherein each group can be readily moved from its storage point to a point of use upon demand.

A related object of the invention is to provide a novel aligning means for insuring that individual trays of samples are not inadvertently misplaced when inserted into the storage compartments so as to interfere with the transfer mechanism.

Other objects and advantages of the invention will become apparent as the following description proceeds, taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a front elevational view of a radioactive sample handling and measuring apparatus embodying the features of the present invention here illustrating the component subassemblies of the apparatus housed in a suitable cabinet or console shown in phantom;

FIG. 2 is a horizontal sectional view taken substantially along the line 22 of FIG. 1;

FIG. 3 is a fragmentary detail view taken in section substantially along the line 3-3 of FIG. 2, and illustrating in particular portions of the tray orienting mechanism;

FIG. 4 is a fragmentary bottom view of a sample tray taken substantially along the'line 4-4 of FIG. 3, such tray here being used for storing discrete radioactive samples and for transporting such samples in seriatim order to a detection station;

FIG. 5 is a sectional view taken substantially along the line 55 of FIG. 4, here illustrating the tray in an upright condition.

FIG. 6 is a plan view of the tray locating and indexing mechanism taken substantially along the line 6-6 of FIG. 3,and illustrating also in broken lines the relative position of a sample tray during an indexing cycle of.

operation;

FIG. 7 is a bottom plan view taken substantially along the line 77 of FIG. 3 and illustrating particularly the details of the locating mechanism and the indexing drive arrangement;

FIG. 8 is an enlarged, fragmentary, plan view of the locating and indexing mechanisms, with certain parts removed for purposes of clarity, here illustrating the locating mechanism in the cocked position prior to latching engagement with the tray and, in phantom lines, the extent of tray movement required to shift the locating mechanism to the uncooked position;

FIG. 9 is a view similar to'FIG.'8, here depicting in solid lines the locating mechanism in the uncooked position, and, in phantom lines, the relative positions of substantially along the line 1010 of FIG. 6 and illus trating particularly the details of the indexing drive mech. anism;

FIG. 11 is an enlarged, fragmentary, sectional view taken substantially along the line 1111 of FIG. 6, here illustrating the details of the tray alignment drive mechanism;

FIG. 12 is a sectional view taken substantially along the line 1212 of FIG. 8 and illustrating details of the locating mechanism;

FIG. 13 is an elevational view, partly in section, taken substantially along the line 1313 of FIG. 8, here depicting the details of the sample or vial sensing mechanism;

FIG. 14 is a plan view taken substantially along the line 1414 of FIG. 1, and illustrating portions of the tray storage and transfer mechanism of the present invention;

FIG. 15 is an enlarged, fragmentary, rear elevation taken substantially along the line 15--15 of FIG. 14 and illustrating particularly details of the vertical and lateral tray transfer mechanisms of the present invention;

FIG. 16 is an enlarged fragmentary vertical sectional view taken substantially along the line 16-16 of FIG. 14

and illustrating the drive arrangement for the vertical tray transfer mechanism;

FIG. 17 is a view similar to view FIG. 16 taken substantially along the line 17-17 of FIG. 14 and illustrating portions of the drive arrangement for the lateral tray transfer mechanism;

FlG. 1 8 is an enlarged fragmentary sectional view taken substantially along the line 18-1 8 of FIG. 15, here illustrating the interaction between the vertical tray transfer mechanism and the rotary tray locating mechanism;

FIG. 19 is an enlarged sectional view taken substantially along the line 19-49 of FIG. 15 illustrating a portion of the drive for the lateral tray transfer mechanism;

FIG. 20 is an enlarged fragmentary, sectional view taken substantially along the line 20-20 of FIG. 14;

FIGS. 21a-21e are fragmentary schematic wiring diagrams of the electrical controls for the apparatus shown in FIG. 1; and

FIG. 22 is a block diagram of a conventional electrical system which accepts, counts, and records the output of a radiation detector.

While the invention is susceptible of various modifications and alternative forms, a specific embodiment thereof has been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that it is not intended to limit the invention to the particular form disclosed, but, on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the invention as expressed in the appended claims.

General organization of an exemplary sample processing apparatus Referring now to FIG. 1, the exemplary embodiment of the invention there illustrated is intended to store a plurality of trays of radioactive samples or specimens and to transfer such trays, one at a time, to a rotary sample indexing mechanism, the latter being adapted to align successive samples in each tray in seriatim order with an elevator mechanism in a radiation detector. To this end, the exemplary apparatus includes an elevator and detector mechanism generally indicated at A, a rotary tray alignment and indexing mechanism generally indicated at B, and tray storage and transfer mechanism generally indicated at C.

As best illustrated in FIG. 1, the various mechanisms A, B and C of the examplary apparatus 36 are mounted in a console or cabinet 31, which is preferably refrigerated for the purpose of lowering the temperature of the samples to an equilibrium level so as to reduce thermal noise which otherwise tends to increase the level of spurious background signals. As here shown, the elevator and detector mechanism A is disposed in the lower end of the cabinet 31 with the rotary sample indexing mechanism B being physically mounted on the upper end of the elevator and detector mechanism. For the purpose of storing a plurality of trays of radioactive samples in readiness for transfer to the rotary sample indexing mechanism B, the apparatus 30 includes left and right sets of 'vertically spaced shelves, generally indicated at 32 and 34 respectively. The arrangement is such that when the tray transfer components of the tray storage and transfer mechanism C are activated, trays 35 of samples 36 are shifted one at a time laterally towards the center of the apparatus 30 where the displaced tray 35 is supported on a vertically movable platform 38, the latter being utilized to lower the tray to a single sample select station defined by the rotary sample indexing mechanism B.

i The cabinet or console 31 is dimensioned such that it defines a compartment 39 at its upper end which is suitable for receiving and mounting certain of the electrical components of the apparatus 30 such, for example, as printed circuit boards and the like (not shown). To provide for control of a sample changing and counting cycle, a plurality of manually operable switches are mounted on the front of the cabinet 31, there being three such switches 49, 41 and 42 shown diagrammatically in FIG. 1. The functions of the switches 40, 41 and 42 will be described more fully in conjunction with the control circuitry (FIGS. 21a-21e) for the exemplary apparatus. For the moment it should sufiice to note that the switch 46 is a Mode Selector Switch, the switch 41 is a Cycles Per Tray Switch, and the switch 42 is a Tray Selector Switch.

To facilitate an understanding of the present invention, the general organization and operation of the elevator and detector mechanism A will be briefly described hereinbelow. Those interested in a more complete operational and structural description of the mechanism A are referred to the copending application of Robert E. Olson, Serial No. 273,110, filed April 15, 1963, now Patent No. 3,198,948, and assigned to the assignee of the present invention.

Referring to FIG. 1, it will be noted that the elevator and detector mechanism A includes a base assembly 44 which houses a pair of light transducers, for example, photomultipliers 45, 46, disposed on opposite sides of a vertical elevator shaft 48. Mounted within the elevator shaft 48 is an elevator 49 having a platform 50 at its upper end for reception of one of the radioactive test samples 36 from the rotary indexing mechanism B and transporting the sample downwardly into the elevator shaft where it is aligned between the photomultipliers and 46. The samples 36 may, merely by way of example, simply comprise a vial or other suitable container within which is placed a liquid scintillator and the radioactive isotope or isotopes to be measured. Thus, as the isotope or isotopes undergo decay events, light scintillations are produced in the liquid scintillator in a manner well known to those skilled in the art, and such scintillations are then detected by the photomultipliers which produce electrical output signals in the form of voltage pulses corresponding to each light scintillation detected. At the completion of the counting cycle, the elevator 49 is returned upwardly to again position the sample 36 in the tray 35 from which it was removed. A shutter mechanism 51 is mounted on the upper end of the base assembly 44 for the purpose of preventing erroneous output signals from the photomultipliers 45, 46 resulting from environmental spectral radiation. At the same time, the base assembly 44 is formed of suitable shielding material such, for example, as lead, which serves to minimize the danger of environmental ionizing radiation causing light flashes in either the scintillation medium or the photomultipliers.

To effect vertical movement of the elevator 49 for the purpose of introducing samples 36 into and ejecting such samples out of the elevator shaft 48, the elevator 49 is drivingly coupled to a conventional reversible motor M1. As here illustrated, this is accomplished by affixing one end of an elevator cable 52 to the elevator 49 at a point 54 intermediate the ends of the latter, the opposite end of the cable 52 being trained about an idler pulle y 55 and a pulley 56 which is eccentrically mounted on the shaft 58 of the motor M1. A second elevator cable 59 is affixed to the lower end of the elevator 49 as indicated at 60, the cable 59 also being trained about the idler pulley 55 and about a second pulley 61 which is mounted eccent-rically on the shaft 58 of the motor M1. The arrangement is such that when the motor M1 is energized to run in a clockwise direction (as viewed in FIG. 1) the cable 50 will pay otf. its pulley61 while the cable 52 will sim-ultaneously pay on its pulley 56, thus lowering the elevator 49, and any sample contained thereon, into the elevator shaft 48. Of course, it will be appreciated that counterclockwise movement of the motor M1 (as viewed in FIG. 1) will serve to pay out the cable 52 and simultaneously pay in the cable 59, thus raising the elevator 49.

The energizing circuit for the motor M1 includes a lower limit switch LS1 (FIGS. 1 and 21a) which is mounted on the frame of the elevator and detector mechanism A in a position to have its actuator LS1 depressed by a laterally projecting flange 62 mounted on the lower end of the elevator when the latter is in a down position with the sample 36 carried thereon aligned between the photomultipliers 45 and 46. Depression of the actuator LS1 serves to \deenergize the motor M1 and the apparatus is then ready for a counting cycle. A second limit switch LS2, included in a second energizing circuit for the motor M1, is mounted on the frame of the elevator and detector mechanism A in position to have its actuator L52 depressed by the flange 62 when the elevator arrives at its uppermost limit position with the sample 36 carried thereon having been returned to the tray 35 from which it was removed. Thus, the limit switch LS2 serves to de energize the motor M1 when the elevator reaches its uppermost limit position. The energizing circuits for initiating clockwise and counterclockwise rotation of the motor M1 will be described more fully in conjunction with the control circuit shown in FIGS. 21a-21e.

Programming logic Since apparatus embodying the features of the present signal, the program control 66 passes a signal over lines 68 and 69 to open a gate 70 and start operation of a timer 71. During the predetermined interval measured off by the timer 71, voltage pulses produced by the photomultipliers 45,46 are passed through an amplifier 72, and the open gate 70, to a scaler 74. At the end of the timed period, the timer supplies a signal over lines 75 and 76 to respectively close the gate 70 and indicate to the program control 66 that counting has been completed. In response to the signal received over line 76, the program control 66 first supplies an actuating signal over a line 78 to a printer 79. The latter is'coupled to the scaler 74 by a channel 80 and thus prints out on a paper tape or the plies a signal to a terminal 85 to signify that the sample in the detector should be changed.

As will be described more fully in conjunction with the control circuit shown in FIGS. 21a-21e, provision is also made for terminating a counting cycle for a given sample prior to completion of the timed period determined by the timer 71 in the event that the operator wishes, for example, to either insert a new sample into the elevator and detector mechanism A, or to position a new tray 35 in the rotary sample indexing mechanism B. Under these conditions, a signal is received on a terminal 86 and passed over a line 88 to the lines 75, 76 to respectively close the gate 70 and indicate to the program control 66 that the counting cycle is to be concluded. Thus, the program control 66 responds to a signal presented on terminal 86 in precisely the same manner as it responds to the signal produced on lines 75 and 76 at the completion of a normal counting cycle determined by the timer 71.

Because the system shown diagrammatically in FIG. 22 may take any of a variety of forms known to those skilled in the art, it need not be illustrated or described in greater detail. It will be understood, however, that the count printed out by the printer 79 will include responses to background radiation which produces scintillation flashes in the liquid scintillator and which is received from extraneous sources, such background responses being in additionto the responses to radiation from the sample being measured. However, this background count can be first measured with no sample, or a sample of known radioactive strength in the detector. The background count can then be subtracted from each sample reading to arrive at an indication of the samples radiation strength.

Besides counting the number of responses by the photomultipliers in a predetermined time interval (preset time operation), the time period required for the generation of a predetermined number of responses (preset count operation) may be measured and recorded, as is well known. Moreover, as is also well known to those skilled in the art, it would be possible to provide a rate meter which permits printing out of counts per unit time, for example, counts per minute. Any of these systems provides an indication of the rate of radioactive emissions, and thus of radioactive strength.

The present invention is concerned primarily with an improved storage and transfer mechanism B (FIGS. 14 and 15) for storing, at spaced points, a plurality of groups of samples containing a liquid scintillator and radioactive substances and with all of the groups being maintained totally independent of one another, and for transferring selected ones of the groups upon demand to and from a sample indexing and selecting station which may subsequently be utilized to process the samples in each group in seriatim order.

The storage and transfer mechanism C is here disclosed in conjunction with a rotary sample indexing system B (FIGS. 3 and 6) which is disclosed and claimed in the copending application of Lyle E. Packard, Roy E. Smith, Alfred A. Munn and Edward F. Polic, Serial No. 273,189 filed April 15, 1963, and assigned to the assignee of the present invention.

In order to facilitate a complete understanding of the present invention, an exemplary rotary tray alignment and indexing mechanism that can be used with the storage and transfer system of the present invention is illustrated in FIGS. 2-13 and will be described in detail below.

Exemplary rotary tray alignment and indexing mechanism In keeping with the present invention, provision is made for positioning a plurality of sample vials 36 in separate compartments formed in the tray (there being twenty-four such compartments in the exemplary tray, here designated by the reference numerals 89-1 through 89-24, as best illustrated by reference to FIGS. 4 through 6 conjointly). The exemplary tray 35 is annular in configuration having an outer peripheral wall 90, an inner peripheral wall 91, and a plurality of radially disposed interconnecting wall 

2. IN A MECHANISM FOR TRANSFERRING GROUPS OF RADIOACTIVE SAMPLES FROM POINTS OF STORAGE DEFINED BY VERTICALLY SPACED SHELVES TO A DETECTOR, THE COMBINATION COMPRISING, A PLATFORM ALIGNED WITH SAID DETECTOR, A CARRIAGE RIGIDLY SECURED TO SAID PLATFORM, MEANS FOR EFFECTING VERTICAL MOVEMENT OF SAID CARRIAGE, A STACK OF TRAY STORAGE SHELVES POSITIONED ADJACENT TO THE PATH OF VERTICAL MOVEMENT OF SAID PLATFORM, A TRANSFER YOKE CARRIED MOVEMENT OF AND MOUNTED FOR LATERAL MOVEMENT RELATIVE THERETO, MEANS FOR SHIFTING SAID YOKE TO A POINT SYMMETRICALLY DISPOSED ABOUT SAID STACK OF TRAY STORAGE SHELVES, MEANS FOR SHIFTING SAID CARRIAGE AND SAID TRANSFER YOKE VERTICALLY WHILE SAID YOKE IS SYMMETRICALLY DISPOSED ABOUT SAID STACK SO AS TO OPERATIVELY ENGAGE SAID YOKE WITH TRAYS IN SAID STACK, MEANS FOR SHIFTING SAID YOKE INWARDLY TOWARDS SAID PLATFORM TO SLIDE A TRAY OF SAMPLES LATERALLY THEREFROM ONTO SAID PLATFORM, MEANS FOR LOWERING SAID PLATFORM TO POSITION SAID TRAY IN ALIGNMENT WITH SAID DETECTOR, MEANS FOR RETURNING SAID TRAY TO A POINT ALINED WITH ITS ASSOCIATED SHELF, MEANS FOR SHIFTING SAID YOKE OUTWARDLY TOWARDS SAID ASSOCIATED SHELF TO RETURN SAID TRAY TO THE SHELF, AND MEANS FOR STEPPING SAID PLATFROM AND SAID YOKE VERTICALLY THROUGH ALL OF SAID SHELVES TO SELECT TRAYS LOCATED THEREON IN SERIATIM ORDER. 